Most healthy adults who weigh at least 110 pounds and are at least 16 years old can donate blood. Beyond those basics, eligibility depends on your medications, recent travel, tattoos, and a handful of health factors that are worth knowing before you schedule an appointment.
Age, Weight, and General Health
The minimum age for whole blood donation is 16 in most states, though some states require you to be 17. Donors who are 16 typically need parental consent. There is no strict upper age limit for donation as long as you’re feeling well and meet the other criteria.
You need to weigh at least 110 pounds. This threshold exists because the standard blood collection bag draws about one pint, and removing that volume from someone with a smaller blood supply raises the risk of dizziness or fainting. Height matters too, since a taller person at 110 pounds has a different blood volume than a shorter person at the same weight. Some donation centers use a height-weight chart to confirm you qualify.
Before every donation, staff will check your vital signs. Your blood pressure needs to fall within an acceptable range, and your hemoglobin (a measure of iron-carrying capacity in your blood) must meet a minimum level. In many countries, the cutoff is 12.0 g/dL for women and 13.0 g/dL for men. A quick finger-prick test at the donation site checks this. If your iron is too low that day, you’ll be asked to come back another time.
Medications That Require a Waiting Period
Most common medications, including those for blood pressure, cholesterol, thyroid conditions, and birth control, do not disqualify you from donating. The deferrals that do exist are mostly about protecting the person who receives your blood from drug residues that could cause birth defects or interfere with clotting.
If you take isotretinoin for acne (sold under brand names like Accutane, Absorica, and Claravis), you need to wait one month after your last dose. Finasteride, used for hair loss or prostate symptoms, requires a six-month wait. These drugs can cause serious harm to a developing fetus if transfused to a pregnant person, which is why the deferral periods exist.
Blood thinners carry their own waiting periods, ranging from two days to seven days depending on the specific drug. Most common anticoagulants like warfarin, apixaban, and rivaroxaban require a seven-day wait after your last dose. The concern here is straightforward: blood that doesn’t clot properly isn’t safe for a recipient who might need it during surgery or trauma.
Tattoos and Piercings
A tattoo does not automatically disqualify you. In most states, if you got your tattoo at a state-regulated facility that used sterile needles and single-use ink, you can donate with no waiting period at all. The same applies to cosmetic tattoos like microbladed eyebrows, as long as they were done at a licensed establishment.
If your tattoo was done in a state that doesn’t regulate tattoo parlors, you’ll need to wait three months. Piercings follow the same logic: if disposable, single-use equipment was used, you’re fine. If a reusable piercing gun was involved, or if there’s any uncertainty about the equipment, the wait is three months.
Travel to Certain Regions
International travel can temporarily disqualify you, primarily because of malaria risk. If you’ve traveled to a region where malaria is present, you cannot donate for three months after returning. This is a notable change from previous policy, which required a full year. If you previously lived in a malaria-endemic area, the deferral is longer: three years. Anyone who has been diagnosed with and treated for malaria must also wait three years and remain symptom-free during that time.
Travel to the United Kingdom is a separate concern. The FDA bars blood donations from anyone who spent a cumulative six months or more in Britain between 1980 and 1997, the period when exposure to the agent that causes variant Creutzfeldt-Jakob disease (the human form of mad cow disease) was at its peak. Short visits don’t trigger the ban, but multiple trips during that window are added together. This policy remains in effect because there is no approved test to screen donated blood for the disease.
Chronic Conditions
Having a chronic illness doesn’t automatically rule you out. People with well-controlled diabetes can donate blood, whether they manage it with diet, oral medications, or insulin. The key factor is that you feel healthy on the day of donation and that your condition is stable.
High blood pressure follows a similar principle. If your blood pressure is controlled with medication and falls within an acceptable range at the time of your appointment, you can donate. Uncontrolled hypertension, where readings are significantly elevated, will typically result in a deferral for that visit. A systematic review of the medical literature found no strong evidence that treated hypertension or mildly elevated blood pressure increases the risk of a bad reaction during donation, but donation centers still check as a general health screen.
Conditions that do permanently disqualify you include HIV, hepatitis B or C, and certain bleeding disorders. If you’ve ever had Ebola, babesiosis, or Chagas disease, you’re also permanently deferred.
HIV Screening and Individual Risk Assessment
For decades, the FDA used blanket deferrals that excluded entire groups of people from donating blood based on sexual orientation. In May 2023, the FDA replaced that approach with individual risk-based screening questions. The new guidelines assess each donor’s specific behaviors rather than categorizing people by group identity.
Under the current system, all donors are asked the same questions about recent sexual behavior. Anyone who has had a new sexual partner, or more than one sexual partner, and has had anal sex in the past three months is deferred. This applies equally regardless of gender or sexual orientation. The change brought U.S. policy in line with the scientific evidence on HIV transmission risk and modern blood testing technology, which can detect the virus within days of infection.
Different Donation Types Have Different Rules
Whole blood is the most common type of donation, and you can give every 56 days (about eight weeks). But there are other ways to donate, each with its own eligibility requirements and frequency limits.
Platelet donation, collected through a process called apheresis where a machine separates platelets from your blood and returns everything else, allows more frequent giving. You can donate platelets up to 24 times in a 12-month period, with at least two days between each session and no more than two sessions in a single week. If a double or triple platelet collection is done in one sitting, you need to wait at least seven days before donating again. The weight requirement is the same 110 pounds as whole blood.
Power Red donations collect a concentrated dose of red blood cells while returning plasma and platelets to your body. Because you’re giving more red cells at once, the waiting period between Power Red donations is longer: 112 days, or about 16 weeks. This type of donation has stricter requirements, including higher hemoglobin levels and, for male donors, a higher minimum height and weight.
What Happens if You’re Deferred
Being deferred doesn’t always mean you can never donate. Most deferrals are temporary. A medication deferral ends once you’ve been off the drug for the required period. A travel deferral expires after the waiting window passes. Even a low hemoglobin reading just means you should try again in a few weeks after eating more iron-rich foods or taking a supplement.
If you’re unsure whether you qualify, most blood collection organizations have online eligibility tools or phone lines where you can check before making the trip. Showing up and being turned away is common and nothing to feel embarrassed about. Roughly 10 to 15 percent of people who arrive to donate are deferred for one reason or another on any given day.